HYMENOPTERA (Gr. membrane-winged), an order of insects, containing a very great number of species, estimated at about one-fourth of the whole class, and of which some, as ants and bees, are singularly interesting and important. They have the mouth furnished with mandibles for cutting and tearing, but the other parts of the mouth are adapted for suction, and are generally narrow and elongated, often united into a kind of proboscis, as in bees. See BEE. The antenna are generally slender, but often exhibit differences in the sexes of the same species. The wings are four in number. the first pair larger than the second, the wings of the same side united in flight by little hooks. The wings. when at rest, are laid one over another horizontally over the body. The wings are entirely membranous, not reticulated as in the neuropteva, but with com paratively few nervures, the arrangement of which is so constant in the whole order that particular names have been given to them and to the space between them, and their diversities have been use of in classification. The wings are want ing in the imperfectly developed females (neuters) of some. Besides the ordi nary eyes. all the hymenoptera have three small simple (or stemmatie) eyes on the top of the head. The abdomen is generally united to the thorax by a slender pedicel. The abdomen of the females is genetaily furnished ,with an organ capa
ble of being bfmt fellifferent purposes ui ditTerent sections of the order, it being in some of the hymenopterous tribes an ovipositor or borer, and in others sting. The hymenoptera in their perfect state generally feed on honey, but some of them prey ou other insects, which are the food of the larvw of a greater number; whilst the larvw of some feed on various vegetable substances. The metamorphoses of the insects of this order are perfect; the larvw are generally—although not in all the families—destitnte of feet; the pupa take no food. The hymenoptera are remarkable for the dilatation of the trachece or air-tubes into vesicles, and the general perfection of the respiratory system. The instincts and even apparent intelligence displayed by some of them—particularly the social kinds, which live in communities—have excited admira tion from the earliest times.—The order is divided into two sections: terebrantia, having an ovipositor; and acyleata, having a poison-reservoir and sting. To the former belong saw-flies, gall-flies, ichneumons, etc.; to the hitter belong ants, bees, wasps, etc.